Mutual solder bond structure and manufacture thereof

PURPOSE: To form a mutual solder bond connection showing an improved fatigue life and stability by hardening a compsn. of an alicyclic epoxide or hardening cyanate ester or its prepolymer with a binder. CONSTITUTION: A binder has a viscosity of about 1000 centipoises or less at the room temp. A filler has a max. grain size of 31 microns and substantially no α-particle radiation. The binder content (of an epoxy and/or cyanate ester) is about 60-25 wt.% of the sum of the binder and filler. This compsn. is filled in a gap between a chip carrier 2 and semiconductor chip 1 soldered thereto through solder bumps 3 and hardened. As the result, a substantially gapless seal with sounder bonds is realized to ensure a highly reliable device and increase the fatigue life of the mutual solder bond.